This invention relates to products for use in a power train, such as a bearing assembly, in environs in which particular attention must be given to cleanliness and/or where resistance to oxidation is paramount, such as in the food or chemical industry. More specifically, this invention relates to a bearing assembly or other products having a cast iron or other housing coated at least in part with a low friction, chemically resistant polymer coating.
In the food, chemical and environmental industries there is a great need for a bearing assembly as well as other products which resists rust, and will not chip, flake or deteriorate in severe wet operating environments or under high pressure washdowns. It is also important, in such environments, that the housings not be subject to corrosion from chemicals normally encountered during use. In the past, for example, cast iron housings of such bearing assemblies have been nickel plated to render the housing resistant to the chemical and environmental demands. In one example, where a ball bearing insert is to swivel into a spherical bore of a ball bearing housing, the housing bore dimensions are controlled to give a specified swivel torque. This procedure is used for a standard line of ball bearings.
When nickel plating is applied to such a ball bearing housing, the spherical bore must be machined oversize to allow for the plating buildup, and requires an additional set up over standard machining operations. Furthermore, due to variations in plating thickness, ball bearing inserts to be used with the plated housings must be graded by size and a trial and error assembly procedure has to be employed to achieve a desired swivel torque with the assembly.
Various and sundry products have heretofore been coated with fluorocarbon polymers such as a polytetrafluorotheylene, or products themselves have been made of such products, particularly to take advantage of low friction characteristics of the polymer. It is also believed, though not known, that bearing inserts may have been produced before and coated with fluorocarbon polymers.
Bearing assemblies and other power train products according to the present invention represent improvement over the prior art. Particularly, bearing assemblies according to the present invention are fully protected from the environment, are more uniform, and, when appropriate, operate at desired assembly torque, levels. Moreover, with coated bearing assemblies according to the present invention, trial and error matching of housings and inserts is no longer necessary.